α,β-Unsaturated Acyl Azoliums from N-Heterocyclic Carbene Catalyzed Reactions: Observation and Mechanistic Investigation
作者:Jessada Mahatthananchai、Pinguan Zheng、Jeffrey W. Bode
DOI:10.1002/anie.201005352
日期:2011.2.11
Caught in the act: Acyl azoliums have long been thought to be key reactive intermediates in N‐heterocyclic carbene catalysis, but they have never been observed under catalytic conditions. Now, this has been successfully achieved by the characterization of α,β‐unsaturated acyl azoliums (see scheme) using different spectroscopic techniques. Kinetic studies revealed the origin of their unexpected chemoselectivity
在行动中被抓住:长期以来,酰基唑鎓一直被认为是 N-杂环卡宾催化中的关键反应中间体,但从未在催化条件下观察到它们。现在,这已通过使用不同光谱技术表征 α,β-不饱和酰基唑(见方案)而成功实现。动力学研究揭示了它们在酰化和环化反应中出乎意料的化学选择性的起源。